Welcome to this e-Tutorial, on why you should use R and how to install it.1
R is a free, open-source, and object-oriented language. Free and open-source means that anyone is free to use, redistribute and change the software in any way. Moreover, “R is ‘GNU S’, a freely available language and environment for statistical computing and graphics which provides a wide variety of statistical and graphical techniques.” (http://cran.r-project.org)
There are lots of software out there to do data analysis that are prettier and seem more accessible than R, so why should I invest in learning R?
If you are not convinced yet, just can type “why to use the R language” in google, and I think the results will speak by themselves.
You can obtain a free R copy on CRAN (Comprehensive R Archive Network) by clicking on http://cran.r-project.org and choosing your appropriate operating system. Check the following .gif on how to do it: